Apparatus for controlling the course of a lateral bore deviating from a vertical well bore



Dec. 29, 1953 J. A. ZUBLlN 2,664,270

APPARATUS FOR CONTROLLING THE COURSE OF A LATERAL BORE DEVIATING FROM 1 A VERTICAL WELL BORE Filed April 19, 1951 I N VENTOR ATTORNEYS Patented Dec. 29, 1953 o it so st" is;

APPARATUS I FOR CONTR OLEING" THE I COURSE OF A LATERAL BORE DE- 'VIKTING FROM A VERTICAL WELL John A. Zublin, Los Angeles, Calif.

Applicaticnnpril 19; 1951'; S'erialNo. 2121;805

The present-invention relates'specifically'to apparatus for controlling the-course cfa curved bore deviatingfrom an existing well bore. Since. the issuance to me of U; S. Letters- Patent 1 Claim: '(Cl. 255-445) Referring to Figure 1, the vertical well borez is indicated at it andthe deviating curvedabore The apparatus illustrated in is indicated at H.

- this figure embra'cesithe outer resilient normally 2,336,338 in 1943- therehas been aconsiderable. F

development in the field of dri1'1ing jlateralbores deviating from existing verticalwellbores and a number of improvements have been. made in l her and a bit driven byzand rotatable; with :said

drivemember, all as more'rparticularly defined. in my copending application (Serial N 0. 6452s.

Due to the fact thatoilebearingstratais often 1 of quite well-defined and limited thickness, lit is 2 highly desirable to be able to control the course of a curved bore deviatingfrom an existing swell bore andit is'the purpose and, object oithepresent invention to provide apparatusjicrminimize ing the tendency of the drill bit to leavethe desired path during the. drilling of a deviatingbore.

More specifically, the present invention has as its purpose the object of provision of an 'apparatus by which certain gravitational and other forces whose efiectwouldbetoscausethe drill: guide to sag and'bringxabout.unwantedrdepartureof the bitfrom the prescribed coursesof the deviating boreare directly absorbed by the wall of the deviating bore being drillediand so neutralized as to avoid unwanted deflection of the'drill bit. Further and more detailed objects of the invention will becomeapparent as the description proceeds, which will beigivenxby reference to the accompanying drawings, in which t Figure 1 is a side .elevational view with parts broken away for clearness, showing the operating portion of the apparatus inserted in a well bore andfwith the initiation of the drilling of a curved bore and embodying adiagrammaticillustration of the advantages attained thereby.

Figure 2 is a cross-sectional view onlineZ-Z- of Figure 1 showing only the outerflexible resilient normally curved drill guide.

Figure 3 is a cross-sectional viewsimilar to Figure 2 of a modified form of the'inventionr Figure 4 is a cross-sectional view similar to Figure 2 of a second modified form of the invention and.

Figure 5 is a cross-sectional view similar-to Figure 2' of still another form of theinvention curved flexibledrill guide l2 which may take-the form of and be constructed similar to the teachings of my U. S. Patent 2,515,365 issued vJuly "18*, 1950.

lengthwise of the guide [2 will-be about nine inches.

Mounted therein is the nonresilient flexible drill bit drive member 55. Thisfiexible drill'bit drive-member I5 is adapted to be connected into thedrill'strihg: which extends tosthesurface of the well to be rotated thereby. The flexible nonresilicnt drill bit drive member :5 extends downwardly through the normally curved resilient drill guide l2 and.

carries at its lower end for rotation therewith the drill bitbody it having the rollers ll. The drill bit bodyl 6' may conveniently be constructed pursuant-to the teachings of my copending application Ser. No. 219,266 filed April 4:, 1951, now Patent No. 2,631,820.

Thearrangement is such that the bit embrac ing the bit body it and the rollers ll is positively driven through rotation of the flexible drill bit drive member i5. The normally-curved flexible resilient drill .guidelz which is frictionally held against rotation imposesa sideward pressureou the bit causing the same to deviate from the vertical bore l 0; A typical flexible resilient drill guidesuch as represented at 52. will have-an over-alllength of approximately 16 feet and its,

curvature may be on a radius of. approximately 16 feet.

It willbe observed that'the cutting face pre sented by thevrollersi llhas a diameter greater mallyjcurved drill guide l2.

resentedata in Figure 1. This is an essentiai feature of this form of apparatus -because;:it:is a

necessary; that the circulating drill fluid employed in the rotarv drilling operation pass upwardly in the annular: space between the wall of the curvedbore being drilled andithe flexible normallyi curved drill guide l2 Ihave-foundwthat this necessary .clearancebe However, I' prefer to. employ about: seveni of the dovetailed'teeth it per complete revolution: of theqdrillguide 2 with apitch OfbhfiSlOliiH": of about twice the diameter of the guide 12, that is; for a drill guide of 4 /2 inchdiameter IOI'Igl-r tudinal' spacing of the 'convolutions oftheslotiifi interiorly vof the: guide i2 lion rotation aeeaavo tween the diameter of the normally curved flexible resilient drill guide such as l2 and the wall of the curved deviating bore such as H permits gravitational and other torsional and weight forces to cause the free end of the apparatus and notably the bit itself to sag downwardly and thus to progressively cut away the lower wall of the curved bore being drilled with the result that unless the effect of these forces is compensated for in some manner, the drill bit will follow a path yielding a bore of the general configuration represented by the dot and dash lines l8 of Figure 1 rather than a true continuation of the curved bore II as indicated at 19 in Figure 1. Furthermore, progress of the bit has been found to be in the manner illustrated by the varying distances bd and b'-ol in Figure 1. Specifically, the bit, at the time that gravitational force is imposed upon it because of its generally horizontally extending position, will proceed downwardly at a rather sharp inclination until the outer wall of the drill guide such as l2 rests upon the lower wall of the curved bore, such as H, being drilled. As soon as the surface of the drill guide such as i2 is supported by the wall of the curved bore, the bit will no longer sag until it has progressed to a point where gravitational and other forces again exert themselves. The first declination is illustrated by the space b nearest the rollers ll of the bit in Figure l. The second space during which the bit is in reality supported against gravitational forces by contact of the drill guide with the wall of the curved bore is represented by the next juz-ztaposed space designated d. The action is repetitious and aggravated as indicated by the spaces indicated b and d, in Figure 1.

This tendency of the bit to be thrown oif its course by gravitational, torsional and other forces has been affirmatively established by surveying instruments and has been found to give an undesired result in that it may well result in the deviating bore missing that area of the producing field strata which it is most desired to penetrate.

To overcome the effect of such gravitational,

torsional and other forces on the apparatus, I have provided at the lower end of the normally curved flexible drill guide l2 laterally projecting elongated skids or shoes designated 293 in Figure 1 and circumferentially spaced about the outer surface of the normally curved flexible drill guide i2. In the preferred embodiment shown in Figure 1 there are three of the skids or shoes 26 as will be seen by reference to Figure 2. The shoes or skids 2i) bear against the surface of the curved bore H and act as supports for the apparatus in such manner that they absorb the gravitational, torsional and other forces that would otherwise cause the bit to be thrown off the desired course.

By virtue of the circumferential spacing of the skids or shoes at ample clear space is provided therebetween to facilitate the flow of the circulating drilling fluid during normal rotary drilling operations. Inasmuch as the gravitational, torsional and other forces are rendered ineffective to deflect the bit, it will progress along the predetermined course indicated at [9 in Figure l.

The normal, unstressed, curved configuration of drill guide it is such that when inserted into the vertical well bore l it exerts its greatest pressure against the side of the vertical bore Iii away from the vertical bore l0 and insures that the rib 20 provided at the inclined lower end will slide into the curved deviating bore H without being caught on the ledge at the point of takeoff of the curved bore II and the vertical bore Ill. The inner, rotatable drive member [3, while free to rotate within the normally curved, flexible resilient drill guide :2, is not free to partake of any substantial relative longitudinal movement therethrough. The specific mountings for the inner rotatable drive member l5 within the normally curved, flexible drill guide l2 form no necessary specific part of the present invention and the details have not been delineated in the drawings.

In Figure 3 I have illustrated a slight modification in which the skids or shoes are designated as 2! and in this instance are symmetrically spaced apart around the circumference of the normally curved flexible drill guide l2. In this way the bit is compelled to travel in precisely the predetermined curved path established for it, whereas in the preferred embodiment of Figures 1 and 2 there is no limitation on the tendency of the bit to move upwardly in compliance with the force exerted by the normally curved flexible drill guide [2.

In the modification of Figure 4 the skids or shoes 22 are of greater thickness than the dis tance represented at a in Figure 1. It will be recalled that this distance represents the difference between the diameter ofthe cutting face of the bit and the diameter of the normally curved flexible drill guide 52. In the form of the invention represented in Figures 1 to 3, the skids or shoes have a thickness approximating the distance a. In the form of the invention illustrated in Figure 4 it is possible, through the employment of skids 22 of greater thickness than the distance a to cause the bit to partake of a greater upward component of movement than would be imparted thereto by the normal forces of the curved flexible drill guide l2. Indeed, in the modification of Figure l this further component is indicated by the small reference character a: so that the thickness of the skids or shoes 22' in Figure 4 as is indicated thereon represents a distance equal to a plus x. In this case, not only are the gravitational and torsional forces neutralized but a positive component is imparted tending to compel the bit to follow a course giving a curved bore a minimum radius.

It will be appreciated that the skids or shoes 22 of Figure 4 may be located at any predetermined point about the circumference of the drill guide to compensate for the torsional forces which would otherwise tend to change the course of the bit and the azimuth of the deviating bore. It will thus be seen that the skids 22 can be arranged in such a manner that the component resulting from gravitational and torsional forces combined will direct the bit in the desired direction.

In the modification of Figure 5 a single skid or shoe 23 is shown as carried by the lower portion of the external surface of the normally curved flexible drill guide i2 so that the bit is free to act in response to torsional and other forces in directions other than a downward direction. Since the oil-producing strata lies in a horizontal plane, the deflections of the bit laterally may not, in some cases, be particularly objectionable and in the form of the invention shown in Figure 5 such lateral deflections may occur. In all instances it will be observed that positive means in provided for supporting the apparatus as it assumes a horizontally projecting position from the inner surface of the bore being drilled, thus minimizing the effect of those forces that tend to draw the bit off its predetermined course.

Having thus described my invention, what I claim is:

Apparatus for drilling a curved bore deviating from an existing vertical well bore comprising in combination, an outer normally curved nonrotatable flexible resilient drill guide, an inner flexible drive member mounted for rotation within said drill guide, a drill bit carried at the lower end of and rotatable with said flexible drive memher, said bit having a cutting face of greater diameter than the diameter of said drill guide, and projections carried on said drill guide at the lower end thereof having greater radial thick- References Cited in the file of this patent UNITED STATES PATENTS Number Name v Date 1,886,820 Lee Nov. 8, 1932 2,344,277 Zublin Mar. 14, 1944 2,498,192 Wright Feb. 21, 1950 2,500,267 Zublin Mar. 14, 1950 2,565,794 Young Aug. 28, 1951 

